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Here's a photo of my "driving" setup. Note the hose from the distributor vacuum advance can to the tee in the choke pull-off hose (which was already there for the diverter valve signal hose) - that supplies full manifold vacuum to the vacuum advance can. Also note the rubber cap on the original pipe that was connected via a hose to the vacuum advance.

The second photo shows the original factory arrangement for show, with the diverter valve signal hose connected to the tee in the choke pull-off hose, and the original vacuum advance hose in place from the end of the pipe (which is a "ported" vacuum source) to the vacuum advance can.

Here's a photo of my "driving" setup. Note the hose from the distributor vacuum advance can to the tee in the choke pull-off hose (which was already there for the diverter valve signal hose) - that supplies full manifold vacuum to the vacuum advance can. Also note the rubber cap on the original pipe that was connected via a hose to the vacuum advance.

The second photo shows the original factory arrangement for show, with the diverter valve signal hose connected to the tee in the choke pull-off hose, and the original vacuum advance hose in place from the end of the pipe (which is a "ported" vacuum source) to the vacuum advance can.

Takes less than a minute to change from one setup to the other.

John that is very helpful thank you.

What do you do with your diverter signal hose when you have the driver setup?

What do you do with your diverter signal hose when you have the driver setup?

Lawrence

Look at the first photo and you'll see the diverter valve signal hose coming up past the emblem on the valve cover - I just tuck it out of the way at the intake manifold (it has a BB in it anyway, as the system is non-functional).

What do you do with your diverter signal hose when you have the driver setup?

Lawrence

Ok that is what I thought, and I have done the samething. I just wanted to make sure that I was not missing anything.

Thanks

Look at the first photo and you'll see the diverter valve signal hose coming up past the emblem on the valve cover - I just tuck it out of the way at the intake manifold (it has a BB in it anyway, as the system is non-functional).

I have a follow-up question regarding resetting the centrifugal advance curve via the springs. Does anyone have any experience with the centrifugal advance curve kit #735-4957 from NAPA? This is the kit for the non HEI, point style GM distributors.

I have weak springs in my distributor allowing my centrifugal to start pulling in advance at 600 RPM. I need to change the springs to hold the centrifugal from coming in until about 1000 - 1500 RPM. I have a 69Z 302 with the idle set at about 900 – 950 RPM.

I purchase this kit recently. The kit comes with three different springs, two different limit bushings, and one set of weights. Unfortunately, neither the kit or NAPA’s web site provide any technical info at what RPM their spring sets allow the advance to start, or what RPM the advance is “all in”. The kit also does not let you know the advance limit on the two bushings.

One last question: has any one weighed original vs. aftermarket/replacement advance weights while fine tuning their distributors?

I can spend some trail and error time experimenting with this NAPA kit but hoped to “cut to the chase” with other’s experience with this kit.

I have a follow-up question regarding resetting the centrifugal advance curve via the springs. Does anyone have any experience with the centrifugal advance curve kit #735-4957 from NAPA? This is the kit for the non HEI, point style GM distributors.

I have weak springs in my distributor allowing my centrifugal to start pulling in advance at 600 RPM. I need to change the springs to hold the centrifugal from coming in until about 1000 - 1500 RPM. I have a 69Z 302 with the idle set at about 900  950 RPM.

I purchase this kit recently. The kit comes with three different springs, two different limit bushings, and one set of weights. Unfortunately, neither the kit or NAPAs web site provide any technical info at what RPM their spring sets allow the advance to start, or what RPM the advance is all in. The kit also does not let you know the advance limit on the two bushings.

One last question: has any one weighed original vs. aftermarket/replacement advance weights while fine tuning their distributors?

I can spend some trail and error time experimenting with this NAPA kit but hoped to cut to the chase with others experience with this kit.

Thanks

Call Eric Jackson at Vintage Muscle Car 937 836-5927. I have had two carbs rebuilt by him (one for my Vette and one for the Z) and a distributor for the Z. He does a great job and very helpful on the phone. He advertises on the Super Car site.

I purchase this kit recently. The kit comes with three different springs, two different limit bushings, and one set of weights. Unfortunately, neither the kit or NAPAs web site provide any technical info at what RPM their spring sets allow the advance to start, or what RPM the advance is all in. The kit also does not let you know the advance limit on the two bushings.

One last question: has any one weighed original vs. aftermarket/replacement advance weights while fine tuning their distributors?

I can spend some trail and error time experimenting with this NAPA kit but hoped to cut to the chase with others experience with this kit.

Thanks

You can work this out yourself if you have a dial-back timing light to "map" the advance curve that results from each change/combination, but it's very tedious. A better approach is to have someone with a Sun machine set the curve up to your specs; Jerry MacNeish does this work all the time, and knows the ins and outs of the OEM weights and springs vs. the aftermarket kit parts.

Lynn, there are a lot of parts that cross reference to the original NAPA part, but instead of listing all of them, just go to your favorite auto parts store and tell them you need one for a 1973 Camaro 350 2BBL.

Old thread I know, I have looked and looked for the part numbers listed above and I have had 0 luck i did find a Wells # 57-7537 that CarQuest was able to order for about 12$ ea I bought one and it spec'd out with my vacuum guage started moving at 3-4" and stopped by 8" - what are we going to do when these are no longer available? IMO this is a important part for tuning Z's

Just wanted to add some current info on the vacuum advance can for the 480 distributor. I am almost done rebuilding the 302 for my '69 Z and after some research realized that this was an important part of my engine assembly. Even though my car ran fairly well previously, I tested the existing B28 vacuum can and it did not function properly (per the specs provided via this forum - Thanks!) and wouldn't hold advance with vacuum applied.

So off to the parts stores I go with my parts number list courtesy of CRG. Most stores (O'Reillys, PepBoys, Napa, Autozone and a couple small stores) did not have the listed part numbers, but were nice enough to order me an advance based on the application (the only way they really know how to look up parts on their computer nowadays). Man I miss the old days with parts books and interchanges and spec books. Of course each one of those were incorrect, with some being B1's, B25's and one with no number stamped in it at all.

While I was at Autozone examining yet another incorrect part, I asked them to see if there was an "1810" in their brand parts list (Duralast) and there was - a "DV1810". Of course they had no specs on this item but I ordered one anyway - at $11.99. It came in today and low and behold, it has B28 stamped in it. Eureka. Oddly, it didn't even come in a box - only a FedEx bag.

During this adventure I checked some of my other Z distributor vacuum advance units. Turns out there was a B1, a B20, and another bad B28, so I ordered three more today when I picked up the first B28. Sure hope they are the same upon arrival.

Once my distributor is set up on the Sun Machine, I'll try to post the resulting performance (vacuum and mechanical advance stats).

Final comment: If you think you may need one in the future, it might be wise to go order a couple while they are still available. Who knows when the supply could dry up....

i am going to change my vacuum source to full manifold vacuum on my 302, i am running ported vacuum now. i was wondering if when i do it will the set idle change ? it`s cold in minnesota right now so i won`t be firing the car up until spring. also wondering what points you guys use in your 302`s, mine are fine for the time being but want a set for stand by. thanks